Sound board for pianofortes and the like



March 3, 1931. SANDER 1,794,550

SOUND BOARD FOR PIANOF'ORTES AND THE LIKE File Feb. 5, 193 2Sheets-Sheet l lave/awn Richard fla/uier Adar/2g.

R. SANDER March 3, 1931.

SOUND BOARD FOR PIANOFORTES AND THE LIKE Filed Feb. 5, 1930 2Sheets-Sheet 2 Inventor Richard 56026567,

4 I I Abtorr-L z Patented Mar. 3, 1931 PATENT? OFFICE RICHARD SANDER, FCUBITYBA, BRAZIL SOUND BOARD FOR PIANOFOBTES AND THE LIKE Applicationfiled February 5, 1930, Serial No.

My invention relates to improvements in soundboards for pianofortes andthe like, and one of the objects of the improvements is to provide asoundboard in which the bridge or b bridges on which the strings aresupported are constructed so that the sound is intensified and improvedIn instruments having crossing strings two bridges are provided, a longbridge curved in the manner of a harp for supporting the descantstrings,and a short one for supporting the crossing bass strings, and on thesaid bridges two pins are provided for each string, the said stringsbeing deflected out of line by one of the pins and turn back into adirection parallel to the line of its main portion by the second pin.

In my improved soundboard the said bridges are divided along theirmedian line thus producing two bridge bars running parallel to eachother a small distance apart in lieu of a single one, and each bridgebar is provided with a series of pins so that each string bears on pinsfixed to both bridge bars. While in constructions now in use in whichboth series of pins are fixed to an integral bridge the pressuresexerted thereon from opposite sides are balanced within the bridge, inmy improved construction the said pressures and the vibrations of thestrings are transmitted to the soundboard. Another object of theimprovements is to construct the bridge for supporting the bass stringsso that the vibrations of the said bass strings are transmitted to apart of the soundboard capable of unimpeded vibration, and

with this object in view my invention con-' sists in supporting the bassbridge on a rockable lever bearing on a suitable portion of thesoundboard and preferably below the bridge supporting the descantstrings;

Thereby the pressures exerted by the descant and bass strings on thesoundboard are compensated, so that the soundboard is relieved of thestrain and is capable of following freely the acoustic vibrations of thestrings.

For the purpose of explaining the invention an example embodying thesame hasbeen shown in the accompanying drawing in which the samereference characters have been 426,128, and in Germany February 2, 1929.

larged scale taken on the line 2-2 of Fig. 3,

gig. 3 is a bottom view of the soundboard, an

Fig. 4 is a detail sectional View on an enlarged scale showing a part ofthe bridge supporting the descant strings.

In the example shown in the drawings two bridges are mounted on thesoundboard e and each bridge is divided longitudinally into two bridgebars (P, d and b, b respectively, the said brid e bars being locatedparallel to each other an a small distance apart. The bridgebars d 03are provided for supporting the descant strings, and the bridge bars b 6supports the bass'strings. The first series of pins t as viewed from theside of the wrest plank is secured to the bridge bars I) and d and thesecond series of pins t is secured to the other bridge bars 6 and (P.The bridge bars can be reinforced relatively to each other by insertingsuitable spacing members such as screws 1' between the same, the saidspacing members preferably ending at points above the soundboard.

The pressures exerted by the strings on the pins 25 in oppositedirections are transmittedythrough the bridge bars (1 d and b, b to thesoundboard, so that also the acoustic vibrations of the strings are alsotransmitted to the said soundboard.

, The bridge 6 b supporting the bass strings is not supported directlyon the soundboard, but on a plate p connected by means of pillars u withthe ends of levers 0 rock ingly supported below the soundboard onbrackets n, the pillars it being passed through holes made in thesoundboard 0. At their Fig.

cant, strings 'lStliLIlSl'llltt6d1tQ a part of the soundboard which has.a .better'fvibration. i

pressure of the levers on the soundboard. Thus the pressure of the bassstrings acts on the soundboard in a direction opposite to the directionof the pressure of the descant strings, so that the said pressures areco1npensated, and the soundboard is relieved of the strain caused by thesaid pressures. Therefore thesoundboard follows the acoustic vibrationsof the strings more freely than in constructions in Which the soundboardis put undertension by t'he pressure of-the strings. I I,

Preferably the strings are"arranged so'that the deepest bass stringis.connected yvith. that part of the soundboard the natural vibrationsof which havexthe greatest amplitude. Tl'ierebytwo of the rocking-levers0 cross each other in the manner shown in f When disposing thc'parts conthe soundboard the room needed for the levers 0 must be taken intoconsideration. i

The highest descant strings are located on a part of the-soundboardwhich has comparatively unfavourable vibrations. In myiinprovedsoundboard the pressure of the-des- For this purpose the end of the,descant bridge d (Z is connected bya rocking lever 0 with agportion ofthe soundboard having a better vibration, as is shown in Fig. For

this purpose the bottornsides of the bridge bars (Z and (l arerecessedor flattened at their J,

ends, as'is shown in Fig. 4, so that the said end which the bridgesupporting the bass strings is mounted, and rocking levers at the sideof the soundboard opposite to the bridge, said rocking levers supportingsaid plate and bearing on the soundboard at a part remote from saidplate.

5. In a pianoforte, a soundboard, bridges, one. engaged vbyflthe descantstrings and the other en aged by the bass strings, a plate on Which thebridge supporting the bass strings -isinounted, and-rocking levers atthe side of the soundboard opposite to said bridge, said rocking leverssupporting said plate and bearing on the soundboard atvparts oppositetothe bridge supporting said desc ant strings.

6. In a pianoforte, a soundboard, a bridge supporting the bass strings,and a rocking lever supporting saidbridge at the part engaged-by thedeepest string and bearing on a part of the. soundboard remote from saidstring and capable of vibration of amplitude.

In a pianoiortqa soundboard, a bridge mounted thereon, strings attachedto said high bridge, and a rocking lever at the side of the soundboardopposite to said bridge, saidlever supporting said bridge atthepartengaging the highest string and, bearing on the soundboard at a partremote, froinsai'dbridge and I V capable of higher vibration,

In testimony whereof I aflix my signature.

RICHARD SANDER.

portions are out of contact with the soundboard, and the said-endportions areconnected V with a plate 1 or the like which is connectedwith the rocking lever 0 located below the 1 soundboard by means of ascrewrh. The intensity of the sound can be vari'ed according to theposition of the fulcrunis a rela- I tively to the length of the rockinglevers 0.

I claim: I

1. In a pianoforte or the like, a soundboard, a bridge fixed thereto andcomprising substantially parallel bars connected directly to v thesoundboard and spaced from one another,

pins secured to said bars, and strings each .j

engaging one of thepins of each bar.

2. In a pianofortem- :the like, a sound board, abridge fixed theretoandcomprising substantially parallel barszconnected directly to thesoundboard and spaced from one an-.

other, means for spacing said 'barsfroin each other, pins secured to.said bars, and strings each engaging one of the-pinsvof each bar! 3. Ina pianoforte, a soundboard, abridge, strings attached to said bridge,and rocking levers supporting said bridge and bearing on a portion ofthesoundboard remote from said bridge. v

4. In a pianoforte, a soundboard, bridges, one engaged by the descantstrings and'the' other engaged by the bass strings, a'plate on

